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Day Sky Node

By Kriss Norde

Day Sky is not a sky generator in the classic sense - it is a physically plausible simulation of daylight based on a geographic location and a time of day. It produces an HDR image you can use as a light map for realistic outdoor lighting.

Overview

Day Sky generates a 32-bit HDR image that represents daylight at a specific time and place. Not a cosmetic sky, but a physical simulation of sunlight + atmospheric scattering.

Main use: feeding a pseudo-physical outdoor lighting setup. Combine it with a cloud generator (Fast Noise) for a visible sky, or use it directly as an environment map for reflections.

Where to find this node

  • Effects Library: Tools > Generator > Day Sky
  • Quick add: right-click in the Node Editor → Add Tool > Generator > Day Sky

Inputs

  • Effect Mask (blue) - optional. Limits the generation to an area.

Setup

Day Sky → Merge 2D (as a background)
    ↓
Day Sky → Sphere Map → Reflect (as an env map for 3D materials)

Controls tab

Location & time

Latitude / Longitude
Geographic coordinates. They affect the sun angle, the sky color and the intensity.
Day / Month / Time
Date and time. They set the position of the sun and so the color (warm at sunrise/sunset, neutral at noon).

Atmospheric parameters

Turbidity
Opacity / clarity of the atmosphere. Raising it gives a "hazier" sky, as if there were mist or pollution. Low = a crystal-clear sky.
Tone Mapping
Compresses the 32-bit HDR dynamic range into the exposure range you want. Needed to view the sky correctly in Rec.709.
Exposure
Adjusts the intensity of the tone mapping.

Advanced controls

Horizon Brightness
Brightness of the horizon.
Luminance Gradient
Width of the horizon → sky transition.
Circumsolar Region Intensity
Brightness of the area around the sun.
Circumsolar Region Width
Size of the area affected by the sun.
Backscattered Light
Atmospheric backscattering (a "halo" effect around the sky).

Use cases

  • Environment map for an outdoor 3D scene - Day Sky → Sphere Map → Reflect. Chrome/glass materials reflect a pseudo-physical sky that depends on the time of day.
  • Static sky background - Day Sky as the composition background with well-tuned tone mapping. For a sky that does not need to be ultra-detailed.
  • Day time-lapse - animate Time from 06:00 to 18:00 = a sky that changes naturally from sunrise to sunset.
  • Lighting reference for grading - use Day Sky as a color reference to match an outdoor shot.
  • Haze / pollution / smog - raise Turbidity for a hazy sky, an industrial or post-apocalyptic mood.

Tips

  • Combine it with Fast Noise for clouds - Day Sky alone = a cloudless sky. Add an animated Fast Noise on top with a Screen Merge for dynamic cloud cover.
  • Animated Time = a fast-forward day. Combine it with an exposure adjusted frame by frame.
  • 32-bit HDR - the output is high dynamic range. You must go through tone mapping or a Gamut (Remove/Add Gamma) before the final SDR export.
  • Paris = latitude 48.85°, New York ≈ 40.71°, Mumbai ≈ 19.08°. Useful to match a real shoot.
  • Turbidity 2-4 = clear sky, 5-7 = hazy, 8+ = heavy smog/pollution.
  • For pro outdoor 3D lighting, prefer a real HDRI (Poly Haven) → Sphere Map. Day Sky is useful for setups where no suitable HDRI is available or for full control over the time/location.